Semantic Web-Based Information Systems: State-of-the-Art ...

Corcho & Gómez-Pérez
Figure 11. Task decomposition of activity 4 (implementation of the ontology translation
system)
lar to the lex (Lesk, 1975) and yacc (Johnson, 1975) languages used for compiler
construction, and that ODESem is based on common rule-based systems.
As in the design activity, the tasks inside this implementation activity are divided
in groups — four, in this case — as shown in Figure 11.
The goal of the first task is to select reusable pieces of code from the declarative
specifications of other ontology translation systems. These pieces of code are selected
on the basis of the results obtained from the first task of the design activity
and can be related to any of the four translation layers.
The next five tasks are grouped together and should be performed almost in parallel,
as shown in the figure. In these tasks, software and knowledge engineers actually
must implement the transformations at the four layers — lexical, syntax, semantic,
and pragmatic — and the additional transformations described in task 3.6. Unlike
in the design activity, we propose to start with the low-level transformations (those
at the lexical and syntax layers) and continue with the more abstract (and difficult)
ones. The reason for the task ordering suggested is that the semantic and pragmatic
transformation implementations usually need to take into account the specific implementations
at the lexical and syntax layers. We are currently developing automatic
tools that transform the declarative specifications in ODELex, ODESyntax, and
ODESem into Java code.
In task 4.7 — declarative specification processing and integration — the software
engineer is in charge of transforming the previous declarative implementations
at all levels, plus the additional transformations, into actual running code, which
will perform the translations as specified in the previous code. In addition, the
software engineer has to integrate the resulting ontology translation system into
another information system (e.g., an ontology tool), if required. Given that most
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